This K24 proposal builds upon a decade of clinical and epidemiologic research in Zambia, where the candidate - Benjamin Chi, MD, MSc - has lived since 2003. The application is timed to correspond with an important midcareer transition, as Dr. Chi returns to the U.S. in July 2015 to coordinate his ongoing global research and training activities from the University of North Carolina at Chapel Hill (UNC). Dr. Chi's career to date has focused on clinical research and effectiveness studies. Through this K24 award, he seeks formal training in the burgeoning field of implementation research. This work will greatly augment his current portfolio in patient- oriented research, allowing him to further explore facilitators and barriers to the successful implementation of proven interventions. He has recruited a multidisciplinary faculty to collaborate and support him in this endeavor, one that reflects the breadth and depth of UNC's resources in implementation research. Candidate: Dr. Chi is a recognized thought leader in the prevention of mother-to-child HIV transmission (PMTCT). He has led high-impact clinical trials and effectiveness studies, and seeks to complement these skills by developing capacity in implementation research. Despite growing investment from NIH and others, there is currently a paucity of such expertise in the field of PMTCT. The rigorous methods developed in domestic implementation research have not yet translated widely in international work, a gap this application aims to address. Mentoring Plan/Environment: Dr. Chi has an established track record in research training, including leadership of two NIH-funded fellowship programs. Because of competing administrative responsibilities, however, his available time for mentorship has become limited in recent years. With K24 support, he will rededicate his efforts in the mentoring of advanced trainees (e.g., postdoctoral fellows, junior faculty) as they look to become independently funded investigators. He will leverage UNC's extensive resources to accomplish this goal, including NIH-funded centers and training programs, networks and collaborations, and global health institutes and departments. Research Plan: Dr. Chi proposes to study the implementation of new point-of-care (POC) technologies for early infant diagnosis of HIV (EID). POC assays hold great promise, but many factors regarding their implementation - including their integration into existing services - are yet unknown. Built upon the framework of a soon-to-begin randomized NIH-funded study, Dr. Chi will identify barriers to EID uptake and measure the fidelity of diagnostic service implementation (i.e., the extent to which the intervention is delivered as designed), comparing POC-based services to the current standard of HIV DNA PCR testing. Using data obtained from this trial, he will model the population impact of POC EID and other, related interventions to determine optimal strategies for rolling-out EID services across different settings. This plan offers a framework for Dr. Chi's training in implementation research while also providing a platform for mentoring future investigators committed to patient-oriented research.